The invention disclosed in this application uses any integer cycle or impulse type modulation and more particularly is designed to work with a method of modulation named Tri-State Integer Cycle Modulation (TICM) which has been previously disclosed in U.S. Pat. No. 7,003,047 issued Feb. 21, 2006 and is now known by its commercial designation, xMax. This new wireless physical layer technology developed by xG Technology Inc., referred to as xMAX, enables extremely low power omni-directional transmissions to be received in a wide area. Using xMAX, significant bandwidth can be made available for supporting various wireless applications. Voice Over IP (VoIP) based cellular services are now being developed using xMAX. In xMAX-based cellular networks both the base station and the handsets will be equipped with an xMAX transceiver. A mobile device (xMAX handset) in such a network will be free to move in an area covered by multiple xMAX base stations. Although the Heterogeneous MAC protocol for multiple base stations is disclosed in the preferred embodiment as being used in these types of integer cycle and pulse modulation systems it can be implemented on any broad band wireless technologies like WiMax, WiBro, WiFi, 3GPP and HSDPA, or any other type of wired or wireless voice or data systems.
A heterogeneous MAC protocol proposed to support VoIP traffic in xMAX wireless networks was described in the pending patent application by one of the inventors of this application, “Heterogeneous MAC Protocol For Forwarding VoIP Traffic On Wireless Networks”, U.S. Ser. No. 12/069,057, the contents of which are included herein. In that application guaranteed timeslots are assigned to forward VoIP packets, temporary timeslots are assigned to forward data packets and contention based access is used to exchange control messages. That application described the MAC protocol in the context of a single base station providing metropolitan wide mobile VoIP service. There is a need to deploy multiple base stations such that coverage areas of adjacent base stations overlap. If each of the base stations were to operate independently then multiple concurrent transmissions in adjacent cells might interfere with each other. Hence, in a patent application “Heterogeneous MAC Protocol for Multiple Base Stations in Wireless Networks”, U.S. Ser. No. 12/380,698, by some of the inventors of this application the MAC protocol was modified to support multiple base stations. In “Improved Heterogeneous MAC Protocol for Multiple Base Stations in a Wireless Network”, U.S. Ser. No. 61/123,888, the contents of which are included herein, an improvement was disclosed to eliminate additional interference points. This application describes a keep alive timeslots based approach to track registered handsets for a MAC protocol that combines contention-free and contention-based MAC protocols for use in wireless VoIP systems with multiple base stations.